类返回类型创建方法

Question

[UML图]时，[1]

下周我学习了期中考试，我练从我的教授给出一些例子;然而，我在类返回类型方法中遇到了一些麻烦。

我附加了UML图以防万一。

我想了解的是Job类中的getPerson方法。我不认为我需要Job类中的数组列表来存储所有员工。因为我在公司类中已经有了一个数组列表。另外，返回类型是Employee类，我不确定如何使用此类返回类型获取人员的信息。

我的问题

1. 公务员getPerson（）{}在作业类
2. 公共布尔isVacant（）{}在作业类
3. 此外，你会介意检查getVacantJobs，getFilledJobs和getAllJobs方法如果这些构建正确？

我用迭代器来显示所有存储的作业。

--------------------------- Employee Class ----------------- ------------

public class Employee { 
    private String name; 
    private int id; 

    public Employee(int id, String name) { 
     this.name = name; 
     this.id =id; 

    } 

    public final String getName() { 
     return name; 
    } 

    public final void setName(String name) { 
     this.name = name; 
    } 

    public final int getId() { 
     return id; 
    } 

    public final void setId(int id) { 
     this.id = id; 
    } 

    @Override 
    public String toString() { 
     return "Employee [name=" + name + ", id=" + id + "]"; 
    } 

} 

---------------------------- Job Class- -------------------------------------

public class Job { 

    private String description; 

    private int id; 
    private double maxSalary; 

    public Job(int id, double maxSalary, String description) { 
     this.description = description; 
     this.id = id; 
     this.maxSalary = maxSalary; 
    } 

    public Job(int id, double maxSalary, String description, Employee e1) { 
     this.description = description; 
     this.id = id; 
     this.maxSalary = maxSalary; 



    } 

    @Override 
    public String toString() { 

     return "Job [description=" + description + ", id=" + id 
       + ", maxSalary=" + maxSalary + "]"; 
    } 

    public final String getDescription() { 
     return description; 
    } 

    public final void setDescription(String description) { 
     this.description = description; 
    } 

    public final double getMaxSalary() { 
     return maxSalary; 
    } 

    public final void setMaxSalary(double maxSalary) { 
     this.maxSalary = maxSalary; 
    } 

    public final int getId() { 
     return id; 
    } 

    public Employee getPerson() { 
     retrun 
    } 

    public final void setPerson(Employee person) { 
     this.id = person.getId(); 

    } 
} 

------ --------------------公司类---------------------------

import java.util.ArrayList; 
import java.util.Iterator; 

public class Company { 

    static ArrayList list = new ArrayList(); 
    Iterator itr = list.iterator(); 


    private String name; 

    public Company(String name) { 
     this.name = name; 
    } 

    public Company() { 
     // TODO Auto-generated constructor stub 
    } 

    public static void addJob(Job j1) { 
     list.add(j1); 
    } 

    public void removeJob(int id) { 
     list.remove(id); 

    } 


    public ArrayList<Job> getVacantJobs() { 
     while (itr.hasNext()) { 
      if ((itr == null)) { 
       System.out.println(itr); 
      } 
     } 
     return null; 

    } 

    public ArrayList<Job> getFilledJobs() { 
     while (itr.hasNext()) { 
      if (!(itr == null)) { 
       System.out.println(itr); 
      } 
     } 
     return null; 
    } 

    public ArrayList<Job> getAllJobs() { 
     while (itr.hasNext()) { 
      System.out.println(itr.next()); 
     } 
     return null; 
    } 

} 

Answer 1

添加字段person至Job类。

public class Job { 

    // ..... 

    private Employee person; 

    public Employee getPerson() { 
     return person; 
    } 

    public final void setPerson(Employee person) { 
     this.person = person; 
    } 

    public boolean isVacant() { 
     return person == null; 
    } 
} 

而且jobs字段添加到Company类。

public class Company { 

    // static ArrayList list = new ArrayList(); // You don't need this 
    // Iterator itr = list.iterator(); // You don't need this. 

    // ..... 

    private ArrayList<Job> jobs = new ArrayList<>(); 

    public ArrayList<Job> getVacantJobs() { 
     ArrayList<Job> result = new ArrayList<>(); 
     for (Job job : jobs) 
      if (job.isVacant()) 
       result.add(job); 
     return result; 
    } 

    public ArrayList<Job> getFilledJobs() { 
     ArrayList<Job> result = new ArrayList<>(); 
     for (Job job : jobs) 
      if (!job.isVacant()) 
       result.add(job); 
     return result; 
    } 

    public ArrayList<Job> getAllJobs() { 
     ArrayList<Job> result = new ArrayList<>(); 
     for (Job job : jobs) 
      result.add(job); 
     return result; 
    } 
}